Art of repairing and strengthening metal bridges of the truss type and like structures



June 1934. A. R. KNIGHT 1,952,820

ART OF REPAIRING AND STRENGTHENING METAL BRIDGES OF THE TRUSS TYPE ANDLIKE STRUCTURES Filed April 1952 -3 Sheets-Sheet l a 8% gm WMy" June 12,1934. KNlGHT 1,962,820

ART OF REPAIRING AND STRENGTHENING METAL BRIDGES OF THE TRUSS TYPE ANDLIKE STRUCTURES Filed April 7, 1932 3 Sheets-Sheet 2 June 12, 1934. RKNlGHT 1,962,820

ART OF REPAIRING AND STRENGTHENING METAL BRIDGES OF THE TRUSS TYPE ANDLIKE STRUCTURES Filed April 1932 3 Sheets-Sheet 5 Patented June 12, 1934UNITED STATES PATENT OFFICE ART OF REPAIRING AND STRENGTHENING METALBRIDGES OF THE TRUSS TYPE AND LIKE STRUCTURES 12 Claims.

This invention relates to the art of repairing and strengthening metalbridges of the truss type and like structures.

A frequent cause of the failure of an iron or steel bridge of the trusstype to bear or properly distribute the maximum load for which it wasoriginally designed is the slack which occurs after long continued usein the brace or link members which take part in distributing the loadand the impulsive forces of trafiic from point to point through thebridge structure to the foundation supports of the bridge. This slack inturn is due either to a permanent stretch of the metal brace or linkmembers beyond their original length or to wear of their eye-portionsupon the pins or bolts of the bridge which attach them at theirextremities to the portions of the bridge structure between which theyextend. Generally both these last-mentioned causes are operative in 20-producing the slack in the brace or link members; and moreover the wearof the eye-portions of these members on their attaching pins so weakensthe structural strength of the brace or link members as to present thisas an additional cause of the failure of the bridge to bear or properlydistribute the load for which it was originally designed.

Furthermore, present-day motor vehicles, of greatly increased weight andspeed of travel even over bridges, as compared with the vehicles andtheir rates of travel but a few years ago, have so greatly increased theloads and the impulsive forces of those loads in traffic which bridgesare subjected to as to render the bridges of a few years ago entirelyinadequate to sustain those changed traflic conditions even when theiroriginal efi'iciency has not been impaired by the factors hereinbeforereferred to. Hence, aside from these factors tending to greatly reduceor destroy the efiiciency of the bridges to sustain and properlydistribute the maximum load for which they were designed, modern trafficconditions have greatly added to the problem of providing adequatebridges without the prohibitive cost of replacing the older by entirelynew bridges designed especially for the heavier loads and greaterimpulsive forces of present-day traflic conditions.

A primary object of my invention is to restore, r with a minimum amountof labor and cost and with little of any interruption to traffic, theoriginal strength and efficient functioning of bridges of the truss typeto bear and properly distribute the maximum load for which they wereoriginally designed where that strength and efficiency in functioninghave been impaired by the factors hereinbefore referred to.

Another primary object of my invention is to increase theload-sustaining and load-distributing capacity of bridges of the typereferred to beyond that for which they were originally designed so as toenable such bridges already in. use, and which would otherwise beinadequate, to sustain the increased loads and their greater impulsiveforces on the bridge structure afforded by present-day vehicles andtraflic conditions.

Addressed to those objects, my invention, broadly stated, pertains toimproved methods of repairing and strengthening, and where necessaryentirely renewing, the brace or link members of metal bridges of thetruss type, or, where necessary to increase the load-sustaining capacitybeyond that of the original design, adding addi tional brace or linkmembers, without appreciable dismantling of other structural parts ofthe bridge.

I am aware that in the prior art to which my invention relates, meanshave been proposed for the ready substitution of a new brace member inthe bridge for one found defective or becom-- ing defective by use, butthe objection to such proposals, from the standpoint of the objectssought to be attained by my invention, is that they require the bridgetobe originally designed and built in some particular manner or withsome special structure enabling or facilitating the substitution of. thenew brace member for the old when occasion requires that substitution.

As distinguished from such proposals, my invention contemplates theready repairing, strengthening or renewal of brace or link members, orthe insertion of additional ones, inall the customary forms of bridgesof the truss type.

I am also aware that in the prior art to which 5 my invention relates,devices have been employed for taking up the slack in the brace or linkmembers of a truss bridge in an endeavor to restore them to theiroriginal condition of functioning. But one objection to such devices,from. the standpoint of the objects sought to be attained by myinvention, is that they do not repair or remedy the weakened structureof the brace or link member itself caused by the wear of theeye-portions of that member on its attaching pins. That wear, ashereinbefore pointed out, is also one of the sources of slack in thebrace or link member between its attached terminals, and thereforetaking up the slack not only does not remedy the weakened structureabout the eyes of the brace or link member but simply imposes an addedstrain thereon which the weakened structure is ill adapted to withstand.The result is that the devices of the prior art to take up the slack inthe brace or link members do not attain the object of my invention ofrestoring the structure to its original strength or load-bearingcapacity, and, of course, do not increase the strength or loadbearingcapacity of the structure above that for which it was originallydesigned, which is another object of my invention.

Except for bridges specially designed for substitution of new brace orlink members for old impaired ones, one reason why the methods anddevices of the prior art last referred to have been restricted simply totaking up the slack or wear in the old brace or link members has beenthe impossibility of removing the old brace or link members from theirattaching pins or bolts in the bridge structure and replacing them withnew members or with the old members repaired in their eye-portionswithout removing and then replacing the attaching pins or bolts whichwould so impair the bridge structure as a whole during this work ofrepair as to entirely interrupt traffic.

One of the particular objects of my invention is to enable the removalor" a worn brace or link member from its attaching pins or bolts and thereplacement on those pins of the old link member so repaired as topresent new eye-portions or an entirely new link member complete withoutremoving those pins or bolts from the bridge structure and withoutappreciable dismantling of adjacent structural parts of the bridge toget at this work of removal and replacement.

Directed to this object, my invention contemplates so cutting a gapthrough the solid metal on one side of each eye-portion of the wornbrace or link member, for example by a cutting torch, as to free thismember from its attaching pins in the bridge structure by a slightlateral movement of the member. The impaired eyeportions of the removedlink member may then be cut off and the shank of the old link memberused, if desired, with new eye portions welded thereto, or an entirelynew link member complete may be substituted for the old one. To

get the thus repaired old link member or the substituted new one back inplace on the attaching pins on the bridge structure, my inven tionfurther contemplates differing forms of eyeportions for those linkmembers and different methods of procedure according to those differingforms of eye-portions.

In one form and method two eye-bars are used to be welded to the shankof the old removed brace member or to a new shank as desired, and withthese eye-bars then forming the two terminal eye-portions of the bracemember. These eye-bars may be substantially the same as the end oreye-portions of the old brace,

having a closed bearing aperture for the attaching pin and hence withsolid metal entirely surrounding the pin. With this form of eye-bars, agap is cut out as before through the'metal of the eye for the placementof the eye-bars on the attaching pins on the bridge structure, and thegap is then closed by the metal piece cut out in forming the gap or by aseparate properly shaped piece as desired and the closure welded inplace to form a solid metal eye structure about the attaching pin, whicheye structure may be reinforced as later described. These eye-bars maybe first thus placed on their attaching pins in the bridge structure andthen welded to the rod or bar forming the shank of the brace member, orthis welding of the eye-bars to the shank may first be done and then thestructure complete as a brace member may be placed on the attaching pinson the bridge structure in the manner just described.

Or, an entirely new brace or link member complete with eye-portions asbefore may be employed, and then the method of placing this completemember on its attaching pins on the bridge structure is also the same aslast described.

According to another form and method, U- shaped or forked eye-bars areemployed and these are inserted in the bridge structure over theattaching pins and the depending limbs of these bars are then welded tothe bar or rod which is to form the shank of the complete brace or linkmember.

In association with these methods and devices of my invention, it isdesirable, and in some cases essential, to employ additional methods andmeans of adjusting the length of the new or repaired brace member, andmy invention contemplates this, not merely for the purpose, as in theprior art devices hereinbefore mentioned, of taking up slack in thebrace or link member consequent upon a permanent stretch in that memberor wear on its eye-portions by long continued use, but to adjust thenewly installed brace member to its proper length for carrying anddistributing its share of the load.

The foregoing objects and principles of my invention and other objectsand principles thereof will more fully appear from the illustrativeexamples hereinafter given of methods of procedure and devices used forthe practice of the invention.

In the accompanying drawings illustrating certain embodiments of myinvention,

Fig. 1 is a side elevation of a portion of a metal bridge of the trusstype presenting one embodiment of my invention;

Fig. 2 is an end view taken on the cross-sectional line 2-2 of Fig. 1through one of the two opposite-side structures of the bridge;

Fig. 3 is a vertical side-elevational view, on an enlarged scale, of oneend portion of a brace or link member of the bridge shown in Fig. 1;

Fig. 4 is an edge .view of a portion of a brace or link member similarto that shown in Fig. 2 except modified to provide two eye-bars insteadof one as in Fig. 3; Fig. 5 is a side elevational view on an enlargedscale of an eye-bar for a brace or link member diifering in form fromthat shown in Figs. 1 and 3, and showing the lines of cut through thehead of the bar to the eye thereof for the insertion of the bar on theattaching pin in the bridge structure;

Figs. 6 and '7 are side and head-end elevational views, respectively, ofthe eye-bar of Fig. 5, and showing a reinforcing plate over the cutabovereferred to;

Figs. 8 and 9 are views similar to Figs. 6 and 7, respectively, butshowing a form of reinforc ing plate somewhat different from that shownin Figs. 6 and 7;

Fig. 10 is a side elevational view of two eyebars with cuts on oppositesides for the insertions of the bars on the attaching pin in the bridgestructure and then the bars welded together to form a single eye-barstructure;

Fig. 11 is a cross-sectional view of the structure shown in Fig. 10along the lines 11-11 of that figure;

Fig. 12 is a side elevational view of a complete brace or link memberformed of two eye-bars properly cut for their insertion on the attachingpins in the bridge structure and with the shank portion of two separatedparts with a lengthadjusting device between them;

Fig. 13 is a side elevational view of a brace or link member without alength-adjusting device and showing lines of cut through the heads ofthe member to the eyes therein enabling the member as a complete wholeto be placed in position on the attaching pins in the bridge structure;and

Fig. 14 is a side-elevational view of the brace or link member of Fig.13, cut through in the center of the shank to divide the member and witha length-adjustment device provided thereon.

Referring now more particularly to Figs. 1 and 2, except for the braceor link members with their eye-bars, these views present a conventionalor usual form of truss bridge of iron or steel, it being understood, ofcourse, that only one of the two opposite sides of the bridge is shown,and only a sufficient portion of that side of the bridge being shown toexemplify the application of the present invention thereto. In Fig. 1the bottom and top rails or runners on the side of the bridge presentedto view are indicated at 10 and 11, respectively, the top rails orrunners only being shown in Fig. 2.

As the construction in such a bridge is substantially the same at thetop and bottom so far as the construction afiects the application of thepresent invention to the bridge, detailed reference need be made only tothe structures at the top. As shown in Fig. 2, there are two top railsor runners 11, 11 on that side of the bridge to which that viewpertains,'the construction being the same on the opposite side. As isthe usual practice, these rails are of substantial thickness and aresurmounted or covered by a relatively thin plate 12.

The vertical columns for supporting the top structure from the bottomrails in such a bridge generally each consist of two solid fiat beamshaving a central rib placed transversely of the runners so that theedges of the beams are presented to the side view of the bridge in Fig.1 as indicated at 13 and the fiat face of one of the beams is presentedto View in Fig. 2 as indicated at 14, its central rib being shown at 15.A lattice work, as indicated at 16 in Fig. 1, generally extends acrossthe open sides of the column, and the column is anchored to the lowerand upper runners of the bridge by plates 17 secured by rivets 18 to thebeams of the column and by a relatively large and heavy bolt or pin 19to each pair of top and bottom rails or runners, that pin or boltextending transversely entirely through the side rails or runners andthe space between them as shown for the top structure in Fig. 2. Thisconstruction, which is the .usual one, leaves side spaces between theanchor plates 17 of the supporting columns and the top and bottomrunners 10 and 11 and also a. center space between the extremities ofthe anchor plates beyond the free ends of the beams 14, as shown forexample in Fig. 2, for anchorage about the pins or bolts 19 of theterminal ends of the diagonally extending brace or link membersnecessary in bridges of the truss type to properly brace the bridge intothe loads to which it is subjected without undue links from part to partso as to properly distribute the strains of the loads and the impulsiveforces on the bridge of those loads in trafiic. In other words, thediagonally extending brace or link members 20 with their eye-bars 21 asshown in Figs. 1 and 2 are in the usual positions of brace or linkmembers in a bridge of the truss type, and the brace or link membersshown differ from those heretofore and customarily used, not in positionin the bridge structure but in construction and mode of attachment tothe pins or bolts 19 of the bridge structure according to the-principlesof the present invention as will later more fully appear.

The brace or link members of truss bridges are generally bars ofrectangular cross section in the shank and with fiat circular heads oreyeportions of substantially the same thickness as the shank and withthe eye-apertures for the attaching pins completely closed; that is,completely surrounded by the metal of the head, so that the attachingpin must be inserted during-the course of construction of the bridge.Except for the lines of cut through the metal of the heads, Fig. 13 is arepresentation of such a brace or link member. Less frequently, brace orlink members of rod shape in the shank are employed, but in all casesthe heads or eye-portions are formed, as stated above, to present solidmetal completely surrounding the attaching pins, such for example as thepins 19 in Figs. 1 and 2.

As hereinbefore stated, in the course of long continued use of thebridge, there is considerable wear on the eyes of the brace or linkmembers about their attaching pins, such as the pins 19 in Figs. 1 and2, which wear produces a slack in the brace or link member between itsattached terminals and thereby the brace or link member fails to sustainor properly distribute its share of the load. Prior to my presentinvention, so far as I am aware, the only way to remove such a wornbrace or link member and to substitute a new one with unimpaired eyes orto repair the member has been to remove the attaching pins or bolts,such as the pins or bolts 19' in Figs. 1 and 2, which were insertedthrough the eyes of the member when the bridge was in process oforiginal construction. This-removal of the attaching pins on bolts wasnot only exceedingly difficult, however, due to the heavy weight of theother structural parts of the bridge supported thereon, as shown inFigs. 1 and 2, but the removal of those pins or bolts left those otherparts so unsupported as to require discontinuance of the use of thebridge until the repairs were completed. Moreover, those repairsrequired not merely replacement of the new or repaired brace or linkmembers but also a restoration of the other parts of the bridge fromtheir unsupported and therefore disaligned positions to their originalpositions for insertion through them of the old or new pins or bolts,with considerable resulting delay and cost. Because of these factors,the practice has been simply to provide some device on the shanks of thebrace or link members to take up the slack therein from time to timeuntil continued wear on the eyes of those members absolutely requiredtheir replacement if the bridge was to be continued in use at all. Whilethe taking up of the slack in the brace or bridge mem bers enabled somefurther use of the bridge, it obviously did not restore those members totheir a relatively rigid structure capable of sustaining,

original load-sustaining and distributing capacity, for the impairmentof the structure of the eyes was not remedied, and the bridge was simplycontinued in use at its lessened load-sustaining capacity.

- In proceeding according to my invention, and assuming that brace orlink members with worn eyes are in place on the belts or pins 19 in thepositions in the bridge shown for the brace or link members 29 in Figs.1 and 2, a gap is cut through the solid metal on one side of eacheyeportion of the worn member, for example by a cutting torch, so as tofree the member from its attaching pin 19 in the bridge structure by aslight lateral movement of the member. In most cases the gap may be cutout along straight lines transversely of the link member as shown inFig. 5, although it is to be understood that Fig. 5 does not show a wornmember but a new one so out according to the principles of myinventionas to be inserted on the attaching pin in the bridge structureas will later more fully appear. With gaps thus cut out through themetal of the two opposite eye-portions of the worn brace or link member,there is generally room in the bridge structure for the removal bodilyof the entire member by lateral movement, and the free space requiredfor that movement may be increased by removal of the adjacent portion ofthe thin cover plates of the bridge runners, one of which, the coverplate of the upper runners, is shown at 12 in Fig. 2. Or thegap throughone of the eyeportions of the member to be removed may be cut on an arcwhose center is the eye at the oppo site end and the cut end of themember removed from the attaching pin at that end by a pivotal movementof the member as a whole on the opposite attaching pin, and then the gapin the still attached eye-portion out along the lines most convenientfor removal of that end of the member. Or, it may be found mostconvenient under certain conditions, to cut through the shank of thebrace or link member so as to leave the opposite end parts freelyswinging fromtheir attaching pins, and then cut the gap to the eye ofeach of these parts along the lines most convenient for the applicationof the cutting torch and removal of the parts.

My invention contemplates several alternative methods and means forrepairing and replacing the worn brace or link member or substituting anentirely new one in the bridge. In one method, the eye-portions of theworn and removed brace or link member are cut off from the shank of themember and two new eye-bars are welded to the old shank, or an entirelynew shank part may be used to which the new eye-bars are to be welded,as desired, these new eye-bars then forming the terminals of thecomplete brace or link member to be inserted on the attaching pins ofthe bridge structure.

The preferred form of new eye-bar of my invention is that shown at 21 inFigs. 1 to 3, inclusive. As shown it consists of a U-shaped barpreferably, although not necessarily, rectangular in cross-section, withthe open end of the bar between its forks adapting the bar to beinserted in the bridge structure upon one of the attaching pins 19 shownin Figs. 1 and 2 so as to position its bend or curved head in bearingand anchored contact on the pin and with the forks of the bar extendingtherefrom clear of the runners of the bridge for the attachment theretoof the rod or bar 20, Figs. 1, 2 and 3, to form the shank of the braceor link member. When a pair of such eyebars are in place in the requireddiagonally opposite positions in the top and bottom runners of thebridge on pins 19, a bar or rod 20 forming the shank part is welded tothe forks of these eye-bars, as indicated by the lines of weld 22 inFig. 3, to form a complete brace or link member, two of such completedmembers being shown in place in the bridge structure in Fig. 1.

The eye-bars shown in Figs. 1 to 4, inclusive, may be formed in any wayfound most convenient or desirable. A straight bar may be bent to theU-shaped form shown, the bending thus forming the eye-aperture forreception of the pin 19 therein in bearing contact against the metal ofthe bar at the head thereof as shown in Fig. 3 and also forming thepassage (between the forks of the bend) from the exterior of that bar tothe eye-aperture for the insertion of the pin 19 into the eye-aperturewhen the bar is brought up to the pin and is moved transversely of theaxis of the pin. Or a solid bar of the boundary contour of the bar shownin Fig. 3 may be employed and a circular eye-aperture first drilledtherein and then a gap cut through the metal of the bar from its stemend to the eye to present the completed bar as shown in Fig. 3.

The bar or rod forming the shank of such a brace or link member may be asingle bar or rod extending from its welded attachment on the forks ofone eye-bar to its like attachment on the companion eye-bar of the pairand without any length adjusting device. But in the preferred form andpractice of my invention the shank rod or bar is divided and the dividedparts threaded, as shown at 23 in Fig. 1 for the cooperation therewithof a turn-buckle member 24 of the usual type operating in threadedrelation with the threads on the rod to form a length-adjusting device.This length-adjusting provision is advantageous for without it a bridgesagging in the part undergoing repair would have to be temporarilybraced up to maintain the proper distance between the opposed eye-barsto be subtended by the shank part of the brace until the weldingoperation was completed, while with the ,lengthadjusting device, theshank part of the brace member may be welded to the eye-bars indisregard of the sag and then the completed member drawn up to eliminatethe sag and to make any further adjustment in the length of the bracemember required toenable it to sustain and dis tribute its share of theload.

Where greater strength in the brace member is required, two of theU-shaped eye-bars 21 may be employed for each end of the brace memberwith the shank rod 20 welded thereto as indicated in Fig. 4. Thisconstruction is especially desirable for brace members intended toincrease the load-sustaining capacity of the bridge beyond that of itsoriginal design so as to meet the conditions of present-day traffic. Asa general rule these brace members with double eye-bars are placedcentrally in the bridge structure shown in Fig. 2 where there is greaterspace about the pin 19 for the two eye-bars of the brace member thereon,the thimble orspacing sleeve 25 shown in Fig. 2 being cut away from thepin 19 to enable the double eye-bars to be placed in position on thatpin.

In some instances, it may be found that the original brace members ofthe bridge, in the positions shown in Fig. 2 as occupied by thebracemembers of my invention, are still in such good functioningcondition as to justify their retention, and the repair required ismerely the insere tion ofad'diti'onal brace members either to bring theload-sustaining capacity of the bridge fully up to that of its originaldesign or to increase it to meet present-day trafilc conditions. In sucha case the additional brace members either of the form shown in Fig. 3or in Fig. 4 are inserted in the central positions already referred to.That is, for one of those positions shown in Fig. 2, the eye-bar or barsof an additional brace member are placed on the pin 19 in place of thethimble 25.

Instead of the form of eye-bars shown in Figs. 1 to 4 inclusive, the neweye-bars may besubstantially the same as the end or eye portions of theold brace or link members which are to be replaced, having a circularaperture or eye drilled therethrough for the attaching pin and hencewith solid metal entirely surrounding the pin. With this form ofeye-bar, shown in Figs. 5 to 12 inclusive, a gap is cut out, as was donein removing the old and worn brace or link member, through the metal ofthe eye for the placement of the eye-bars on their attaching pins, thepins 19 of Figs. 1 and 2.

Differing lines of cut may be employed in making the gap, either onstraight lines transversely of the bar, as indicated at 26 in Figs. 5, 6and 8, to the eye-aperture 2'7, or on oblique lines to the stem of thebar where it joins the head or eye portion as indicated at 28 in Fig.12, the advantage of the latter being that it disposes the lines of cutfarther from that portion of the eye, indicated at 29, in Figs. 5 and12, which must bear the greatest strain when the brace member is inposition and in use. In other words, the oblique lines of cut shown inFig. 12 present more solid metal for the bearing strain on the bracemember than do the transverse lines of cut shown in Fig. 5.

A pair of these eye-bars, as thus cut, may first be placed on theirattaching pins, the pins 19 in Figs. 1 and 2, in diagonally oppositepositions on the top and bottom structure of the bridge and then the rodor bar to form the shank part of the brace for that pair brought intoposition for welding to the diagonally opposite eyeba-rs. Or the weldingof the eye-barsto the shank part may first be done and then the unitedeye-bars and shank part, as a single member, may be inserted, by thegaps in the eye-bars, on the proper attaching pins inthe bridgestructure.

Preferably, however, the eye-bars of the form shown in Figs. 5 to 12inclusive are made long enough so that with a length-adjusting deviceattached between the two eye-bars of a pair at their stem ends, thatdevice and the eye-bars together will form the complete brace or linkmember without the necessity of an additional shank part. Such a braceor link member is shown in Fig. 12. The length-adjusting device may beof any desired form and construction adapting it for itslength-adjusting function and for connecting the two eye-bars so as toform the required rigid brace or link member of the bridge.

In the construction shown in Fig. 12, a tapered hole is drilled in thestem end of each eye-bar of the pair (or, if necessary for thickness andstrength of metal, in the stem end of two eyebars placed together oneach side and Welded together as shown in Fig. 11), and the tapered endof a screw-threaded lug-30 is placed in each said tapered hole andwelded in place to the eye-bar. A turn-buckle member 31 of the usualtype opcrating in threaded relation with the screw lugs then completesthe connection between the eyebars as well as completing thelength-adjusting device.

After the gap is cut in the new eye-bars a nd they are inserted on theirattaching pins 19' in the bridge structure, the gap is filled in eitherby the metal piece cut out in forming the gap or by a separate properlyshaped piece, and the filling piece, indicated at 32 in Figs. 5, 6, 8,10 and 1 2, is welded in place to the head of the 'eye bar.

When the lines of cut in forming the gap in the eye-bars are transverseof the axis of 'the eye-bar as shown in Figs. 5, 6, 8 and 10, Ipreferably reinforce the head of the eye-bar by a side plate weldedthereto over the lines of 'cut of the gap and the welded filling piece,as indi-' cated by the plate 33 of segment form in Figs. 6 and 7.Generally the segment form of reinforcing plate is sufiicient for thepurpose, but if de-' sired the reinforcing plate may extend in circuslar form completely over one side of the head of the eye-bar as shown bythe plate 33' in Fig. 8'.

In localities where the metal of the bridge is particularly subject todeterioration from weather, especially rusting, it has been found thatthe metal of the eye-bars is thus attacked more frequently at thejuncture of the stem with the eye-portion or head of the elsewhere andits load-sustaining capacity thereby weakened. To counteract thisweakening of structure, I extend the reinforcing plate in a tailformation along one side of the stem of the side-bar as indicated at 3.4in Fig. 8. 1 v

Another provision for reinforcing the eye-bars is embodied in the formshown in Figs. 10 and 11. In this form, two eye-bars for each end of thebrace or link member are employed, each identical with the singleeye-bar shown in Fig. 5. Gaps are cut out they are then inserted in thebridge structure on the same attaching pin, for example, the pin 19 inFig. 2, but in a manner to extend the lines of cut of the gaps inopposite directions from'the alined eye-apertures of the two bars, asshown in the full and dotted lines in Fig. loahd in Fig. 11 by thelocations of thefilling The filling pieces for the two gaps are thenwelded in place, and the two bars welded together side by side as shownin Fig. 11 to form the united bar. When this double form of eye-barshown in Figs. 10 and 11 is used, the eye-bars for the opposite ends ofa brace member must of course be inserted on their attaching pins 19before the length-adjusting device 30, 31 shown in'Fig. 12 is attached.That procedure is also required, even with the single form of eye-bar,when the gap is cut out on the oblique lines shown in Fig. 12, for thoseoblique lines ofjthe gap will not permit the placement of the brace as.a completed whole on diagonally opposite pins 19 in the bridgestructure.

Fig. 13, however, represents a complete brace er -link member withthegap in the eye portions on lines of out which does permit the place.-ment of the member on diagonallyopposite pins 19 in the bridgestructure. The left-hand head of the member, as the parts arelviewed inFig. 13, has the gap cut on straight oblique lines 35, while the gap'inthe opposite head is cut .on arcs 36 from the eye of the first-mentionedhead as a center. This enables the head with .the gap cut on the obliquelines 35 to be f rst placed in position on its attaching pin 19 in thebridge structure and then the entire brace member pivbar than in each ofthese two eye-bars,

pieces" 32 in position in the length-adjusting justing device is V witha passage 6 oted on that pin into position inserting the opposite pinthrough the curved gap in the other head of the member.

With the brace member shown in Fig. 13 thus bridge structure, there isno provision, however, for an adjustment of the length or" the member,and Fig. 14 represents a length-adjusting device with which the bracemember may be equipped after it is in place in the bridge. Thelength-adjusting device comprises two pairs of opposed blocks 37, 3'7and 38, 38, one pair for each side edge of the shank of the brace memberand with the blocks having angular base projections adapted to fit intonotches cut in the side edges or" the shank, the blocks then beingwelded in place on the shank, so that a fixed mounting of the blocks onthe shank of the brace member is secured not only by the welding butalso by the fitting oi the blocks to the notches in the shank. Each pairof blocks is provided with opposed threaded lugs 39 with which aninternally threaded turnbuckle member 40 cooperates to complete thedevice. When the lengtheadthus mounted on the shank of the brace member,the brace member is divided by cutting through the shank so as topresent the length-adjusting device as the connection between thedivided parts, as shown in Fig. 14.

With all of the constructions shown, when used in the manner described,brace or link members with new eye-bars may be substituted for the oldmembers with their worn eye-bars without substantial dismantling of thebridge. Generally, it will be found that sufficient access to the partsof the bridge structure required for the removal or" the old bracemembers and the substitution of the new ones in the manner described maybe had without removing any part of the bridge except the old bracemembers, and at the most where access for the work to be done isparticularly difficult, it will require only the removal of the thincovering plates 12 of the bridge runners.

While the principles of my invention both as to methods and means usedhave been'described as applied to and embodied in a bridge structure,the procedural and structural principles of the invention are notconfined thereto but may be applied to and embodied in other organizedstructures requiring removal and replacement of members thereof or theinsertion of additional members. It is therefore to be understood thatthe examples given of the practice of the invention are merelyillustrative of the principles thereof, and that other methods anddevices may be included in those principles within the scope of theappended claims.

What is claimed is:

1. The method of mounting a metal bar on a pin in metal bridges andother structures having the pin accessible for said mounting onlybetween its ends, said method comprising forming the bar with anaperture adjacent one end to receive said pin in bearing contact withmetal of said bar and from said aperture through a portion of said barto an outer boundary surface at a point spaced from said end adapted toreceive said pin between its ends and pass the same into said apertureby movement of said bar upon said pin, and executing said movement tomount said bar on said pin so as to dispose the pin in said aperture inbearing contact with solid metal of the bar between said aperture andthe adjacent end of the bar.

2. The methodof connecting astruotu-ra'l mem ber with a pin in metalbridges and other structures having the pin accessible for forming saidconnection only between its ends, said method comprising forming a barwith an aperture adjacent one end to embrace said pin and with a passagefrom said aperture through a portion of said bar to an outer boundarysurface at a point spaced from said end adapted to receive said pinbetween its ends and pass the same into said aperture by movement ofsaid bar upon said pin, executing said movement to mount said bar onsaid pin so as to dispose the pin in said aperture in bearing contactwith solid metal of the bar between said aperture and the adjacent endof the bar and then securing said structural member to the free end ofsaid mounted bar.

3. The method of inserting a link member between oppositely disposedpins in metal bridges and other structures having said pins accessiblefor connecting said link member thereto onlybetween the ends of thepins, said method comprising forming an eye-bar for each end of saidlink member with an eye-aperture adjacent one end of the bar to receivethe pin and with a passage from said aperture through a portion of saidbar to an outer boundary surface at a point spaced from said endadaptedto receive said pin between its ends and pass the same into saidaperture by movement of said bar upon said pin, executing said movementto connect each of said bars with the corresponding pin so as to disposethe pin in the aperture of the bar in solid metal of the bar betweensaid aperture and the adjacent end of the bar, and then attaching saidlink members to the free ends of said bars.

4. The method of forming a brace-member connection between oppositelydisposed pins in metal bridges and other structures having said pinsaccessible for connectionthereto only between their ends, said methodcomprising forming an eye-bar for each end of said brace-memberconnection with an eye-aperture adjacent one end of the bar to receivethe pin and with a passage from said aperture through a portion of saidbar to an outer boundary surface at a point spaced from said end adaptedto receive the pin between its ends andrpass the, same into saidaperture by movement of said bar upon said pin, executing said movementto connect said bars with said pins so as to dispose each pin in theaperture of the corresponding bar in bearing contact with solid metal ofthe bar between the aperture and the adjacent end of the bar, and thencompleting said brace-member connection by securing to the free ends ofsaid eye-bars a screw device adapted to adjust the length of thecompleted brace-member connection between said pins.

5. The method of connecting a structural member with a pin in metalbridges and other structures having the pin accessible for forming saidconnection only between its ends, said method comprising employing aU-shaped bar adapted to be inserted upon the pin between its ends withthe forks of said bar extending from said pin, thus mounting said bar onsaid pin, and then securing the structural member to the forks of saidbar.

6. .The method of connecting a metallic structural member having aterminal portion provided with a circular eye-aperture with a pin in ametal bridge or other structure having said pin accessible for saidconnection only between its ends, said method comprising cutting a gapthrough the body of said terminal portion from a point in an bearingcontact with outer boundary surface thereof spaced from the adjacent endof said member to said eye-aperture adapted to receive said pin betweenthe ends and pass the same into said aperture by movement of said memberupon said pin, executing said movement to connect said member with saidpin so as to dispose the pin in said aperture in bearing contact withthe solid metal of said member between its eye aperture and its adjacentend and then closing said gap.

7. The method as in claim 6 and in which said gap is closed by a fillingpiece of metal welded in place to the terminal portion of saidstructural member.

8. The method as in claim 6 and in which the gap in the terminal portionof said structural member is closed by a filling piece of metal weldedin place and then a reinforcing plate is welded to one side of saidmember over said welded-in filling piece.

9. The method of connecting a metallic link member having oppositeterminals provided with circular eye-apertures with oppositely disposedpins in a metal bridge or other structure having said pins accessiblefor said connection only between their ends, said method comprisingcutting a gap through the body of one of said terminals from a point inan outer boundary surface thereof spaced from the adjacent end 'of saidmember to its eye-aperture along straight member to its eye-aperturealong an are from the opposite eye-aperture as a center in a manner topass the pin for said other terminal through said gap by pivotalmovement of said link member when said first-mentioned terminal isconnected to its pin, and connecting said terminals.

10. The method as in claim 9 and in which the length of said link memberis adjusted after it is connected with said pins by welding a screw thenadjusting 11. The method of connecting a structural passage from saidaperture through the body of the bar on one side of the aperture to anouter boundary surface at a point spaced from the adjacent end of thebar adapted to receive said pin between its ends and pass the same intosaid aperof said pin, welding the mounted bars together, and thenwelding said structural member to said bars.

12. The method of removing brace or link or other structure in methodcomprising cutting a gap through the body of said terminals to theeye-apertures adapted to withdraw the 01d and then cutting a gap eachterminal of the new member at an the longitudinal axis of the member tothe eye-aperture therein member.

A. RHODES KNIGHT.

